After months of fretting over “tea party”-powered Republican enthusiasm, Democrats say they are seeing signs that their supporters are getting revved up in time to close the so-called “enthusiasm gap” by the Nov. 2 midterm elections.

The Democratic National Committee on Monday announced an impressive cash haul of $16 million during September, 80 percent of it coming from small-dollar and mailed-in donations. Party leaders pointed to the donations and to turnouts at President Obama’s college-campus rally last week in Wisconsin and at the “One Nation Working Together” rally in Washington on Saturday as signals of grass-roots interest in boosting the party.

“We probably caught a lot of the pundits and television commenters by surprise who had basically already written their stories for Election Day declaring Democrats dead,” White House communications director Dan Pfeiffer said Sunday.

“You saw a great turnout [Saturday], just as we saw with President Obama in Madison. And so I think it was a good time. We have a lot more work to do between now and Election Day, but we’re making progress.”

But Republicans say the real test is voter turnout - a metric they won hands down in the primary season.

“In 2006, Democrats had 3 million more primary voters than Republicans,” Republican National Committee spokesman Doug Heye said. “In 2010, that number has turned on its head, with more than 3 million more Republicans voting in primaries than Democrats. So what we see isn’t so much an enthusiasm gap than it is a turnout gap.”

Democrats point to several polls that show the generic ballot tightening. The RealClearPolitics average of generic ballot polls has closed in recent weeks, and as of Monday stood at 46.5 percent to 43 percent in favor of Republicans.

Republicans cite a polling advantage when surveys are broken down by likely voters.

“The further over you go towards being likely to vote, the better the Republicans tend to do,” GOP strategist Mike McKenna said. “That suggests to me that the enthusiasm is still pretty significantly on the side of the Republicans.”

The RNC has yet to publish its September fundraising numbers, and its recent reports have disappointed party activists, who had hoped the RNC could keep pace with the DNC. But Mr. McKenna cautioned that the party apparatus is not all-important this cycle, with Republican donors pumping much of their money to outside groups, such as American Crossroads or American Action Network.

“GOP voters are incredibly unified this year, and most Republican candidates don’t have much room to grow with their base over the final month of the campaign,” Public Policy Polling director Tom Jensen wrote in a recent blog post. “There’s no guarantee that the undecided Democrats will end up coming home, but more than likely they will. Last year’s New Jersey governor’s race is a good example of this.”

On Monday, White House press secretary Robert Gibbs said Mr. Obama’s stepped-up engagement on the campaign trail has boosted Democrats’ chances this fall.

“I think the president has made the case effectively about why people need to be involved and what’s at stake,” he told reporters.

One Democratic strategist also pointed to Gallup’s job-approval numbers for Mr. Obama, which showed traditional Democratic demographics still supporting him, including more than 90 percent of blacks and more than 60 percent of Hispanics. Among self-identified Democrats, his approval is 81 percent, but among self-identified liberals it’s a slightly lower 73 percent - suggesting he has shed some support on his left flank.

In particular, Mr. Obama has been focusing on young voters, a key voting bloc in his presidential campaign but one that’s historically less likely to show up to vote in non-presidential races. To help counter that trend, Mr. Obama is hosting another rally Sunday, this time in Philadelphia and featuring hip-hop group the Roots, which hit the trail with him in 2008.

The One Nation event, put together by progressive groups, unions and civil rights organizations, followed a rally hosted by Mr. Obama at the University of Wisconsin at Madison that drew 26,000 people. Vice President Joseph R. Biden Jr. also drew an overflow crowd at Penn State University last week.